Sadness, feeling down, having a loss of interest or pleasure in daily activities – these are symptoms of depression familiar to all of us.
Depression is a mental health disorder, a psychiatric condition. Specifically, it is a mood disorder characterized by persistently low mood in which there is a feeling of sadness and loss of interest.
Depression is known by different medical terms, some of which signify a particular diagnosis:
- Clinical depression
- Major depression
- Major depressive disorder
- Persistent depressive disorder
- Dysphoric disorder.
Depression is a persistent problem, not a passing one – the average length of a depressive episode is 6 to 8 months.
Depression is different from the fluctuations in mood that we all experience as a part of a normal and healthy life. Temporary emotional responses to the challenges of everyday life do not constitute depression.
Likewise, even the feeling of grief resulting from the death of someone close or other kind of loss is not itself depression if it does not persist.5 Depression can, however, be related to bereavement – when depression follows a loss, psychologists call it a “complicated bereavement.
Similarly, discouraged mood that results from the disappointment of a life event such as a financial problem, a serious illness, or even involvement in a natural disaster, does not necessarily mean depression.
Unipolar versus bipolar depression
A separate condition may be diagnosed if it is characterized by both manic and depressive episodes separated by periods of normal mood, in which case the mood disorder is not depression but bipolar disorder, which used to be known as manic depression or manic-depressive illness.
Unipolar or major depressive disorder is estimated to be 3.5 times more prevalent than bipolar spectrum disorders.
Unipolar depression may be described as mild, moderate, or severe, and can involve anxiety and other symptoms – but no manic episodes. However, nearly 40% of the time over a 13-year period, individuals with bipolar disorder are depressed, making the two conditions difficult, and important, to distinguish.
This diagnosis is characterized by depression accompanied by psychosis.
Psychosis can involve delusions – false beliefs and detachment from reality – or hallucinations – sensing things that do not exist.
Women often experience the “baby blues” with a newborn, but postpartum depression – also known as postnatal depression – is more severe and estimated to affect about 1 in 10 women who have given birth.
Seasonal effective disorder
Often abbreviated to SAD, seasonal effective disorder is related to the reduced daylight of winter – the depression occurs during this season but lifts for the rest of the year and in response to light therapy.
Countries with long or severe winters seem to be affected more by SAD.
Causes of depression
The causes of depression are not fully understood and may not be down to a single source. Depression is likely to be caused by a complex combination of factors:3,5,6,9
- Biological – with changes in noradrenergic, dopaminergic and serotonergic neurotransmitter levels theorized
- Psychological and social/psychosocial.
Some people are at higher risk of depression than others – risk factors, which play into the above causes, include:
- Life events – for example, unemployment, divorce, poverty, although these events lead to lasting, severe depression usually only in people predisposed to it
- Personality. Failure of adaptive mechanisms/coping strategies to stressors
- Genetic factors. First-degree relatives of depressed patients are themselves at higher risk, and occurrence of depression between identical twins is high. Genetic factors may influence individual responses to events that trigger depression
- Childhood trauma can cause long-term brain changes affecting responses to fear and stress. Other history also raises the risk, including a suicide attempt, or any form of abuse – sexual, physical or substance
- Some prescription drugs – including corticosteroids, some beta-blockers, interferon, and reserpine – can lead to depression.
- Abuse of recreational drugs – including alcohol, amphetamines – can accompany depression or result in it. There is a high level of comorbidity between drug abuse and depression
- A past head injury
- Past diagnosis of depression – people who have had an episode of major depression are at higher risk of a subsequent one
- Chronic pain syndromes in particular, but also other chronic conditions, such as diabetes, chronic obstructive pulmonary disease, cardiovascular disease.
Symptoms of depression
The criteria used to make a diagnosis of depression are based on the symptoms that are present, so the list of possible symptoms is similar:3,5,10
- Depressed mood – feeling sad or low
- Reduced interest or pleasure in activities previously enjoyed, loss of sexual desire
- Unintentional weight loss (without dieting) or low appetite
- Insomnia (difficulty sleeping) or hypersomnia (excessive sleeping)
- Psychomotor agitation (for example, restlessness, pacing up and down), or psychomotor retardation (slowed movements and speech)
- Fatigue or loss of energy
- Feelings of worthlessness or guilt
- Worsened ability to think, concentrate or make decisions
- Recurrent thoughts of death or suicide, or attempt at suicide.
Signs are the features that may be noticed by the doctor and others – as opposed to the symptoms that patients can describe themselves. Signs of a person with depression include:5
- Appearing miserable, tearful eyes, furrowed brows, down-turned corners of the mouth
- Slumped posture, lack of eye contact and facial expression
- Little body movement, and speech changes (for example, soft voice, use of monosyllabic words)
- Gloomy, pessimistic, humorless, passive, lethargic, introverted, hypercritical of self and others, complaining.